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Re: Omnivorous dinosaurs

Karen Casino writes:

Are there any anatomical features that indicate omnivory (sic - what would this word be?), and if so, do any dinosaurs have them? Is there a distinction between omnivores that can eat a variety of foods and those that have to eat a variety of foods? What distinctions are made between opportunistic feeding (the grass-eating dogs and chicken- eating mules of the world) and genuinely omnivorous behavior?

Firstly; there is almost no such thing as a pure carnivore or herbivore. Most carnivores get some sort of plant matter in their diet, if only in the form of another animal's gut contents. Herbivores also get a reasonable amount of protein swallowing insects and the like that cling to vegetation (in fact, a lot of parasitic organisms rely on it). The lines between carnivore, onmivore and herbivore can get fairly blurry.

It can be extremely difficult to tell with any degree of certainty from fossil remains exactly what range of foods any particular species ate. Coprolites may be an exception - although identifying which species made them isn't easy. I'm fairly sure that no-one has ever found dinosaur coprolites with both bone bone fragments and plant matter in them though.

Ornithomimosaurs have been suggested to be omnivores mostly because they were theropods (a primarily carnivorous grouping at the time) with no specific carnivorous adaptations (such as sharp teeth or recurved claws). They could still have swallowed small animals whole though. If so, they may never have eaten much in the way of plant matter at all.

Muttaburrasaurus and ceratopians in general have been suggested to be partially carnivorous, due to the shearing nature of their dentition and their powerful jaw muscles. Of course just because a creature was physically capable of doing something doesn't mean it was necessarily part of their behavioural repertoire.

See also the 'dinosaur diet' thread from 1997:



Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com